Fixation clamp with thumbwheel

ABSTRACT

A fixation clamp, more particularly for use in an external fixation system for holding bone fragments adjacent to each other with the help of fixation elements, has at least one clamping assembly having at least one reception opening to accommodate a fixation element along the longitudinal axis of the reception opening. At least one locking element extends through the clamping assembly which locking element provides a clamping force to clamp the fixation element upon tensioning the locking element. The fixation clamp further comprises an actuation element which is in connection with the locking element such that the locking element is actuateable by means of the actuation element, and the actuation element is designed such that it is detachable from the locking element after use and that remounting onto the locking element is prevented after having detached the actuation element from the locking element.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/302,619, filed on Nov. 22, 2011 which claims priority fromEuropean Patent Application No. 10 194 944.4 filed Dec. 14, 2010, thedisclosures of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a fixation clamp and, moreparticularly, to a fixation clamp for use in an external fixation systemfor holding bone fragments adjacent to each other.

External fixation systems are widely used to connect two or more bonefragments to each other. Such systems comprise bone screws, pins, wireswhich are inserted directly into the bone material and these systems useexternal structural elements as fixation rods, bars and rings. In orderto connect the rods and bars to form a rigid frame, fixation clamps areused. Furthermore, fixation clamps are used to connect this screws andpins to the rigid frame to specifically hold bone fragments at anintended place.

One adjustable fixation clamp is known from U.S. Pat. No. 6,080,153comprising two pairs of jaws allowing clamping of a rod as well as of apin.

A clamp for multiple rod-shaped elements is known from U.S. Pat. No.7,618,417 having one single pair of jaws. However, such a clamp allowsclamping more than two, e.g. three or four rod-shaped elements as pinswith one single clamp, thus reducing the number of clamps. However, onefurther fixation clamp is necessary to fix the rod of said clamp to theframe of the fixation system.

U.S. Patent Application Publication No. 2006/0287652 mentions that usualfixation clamps as e.g. known from U.S. Pat. No. 6,080,153 allowclamping of one single screw or pin to the frame and that this way toattach pins or rods leads to bulky fixation systems. Therefore U.S.Patent Application Publication No. 2006/0287652 discloses a fixationclamp addressing this problem and comprises two pairs of jaws withinwhich each pair of jaws allows the introduction and clamping of two rodsor pins etc. at the same time.

These clamps according to the prior art either provide differentdiameters of the receptions provided by the jaws to introduce differentsizes of rods, pins or wires, or they rely on additional inserts as e.g.disclosed in U.S. Patent Application Publication No. 2008/065068. Suchinserts reduce the diameter of the reception cavities to allow a securefixing of differently sized rods, pins or wires.

From U.S. Patent Application Publication No. 2010/0298827 a furtherfixation clamp is known. Although the users such as surgeons providevery good feedback concerning the handling of such a fixation clamp,many of the users mentioned clamping process in some occasions isdifficult.

Furthermore the fixation clamps as known from prior art have thedrawback that the user is not able to recognize, if the fixation clamphas been sterilized or if it was already used.

BRIEF SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide a fixation clampwhich provides an easier clamping process, in particular the fixationclamp shall be pre-tensioned manually or hand-operated respectively, andtensioned by means of a tool, such as a wrench.

Such an aspect is solved by the features of claim 1. Accordingly afixation clamp, more particularly for use in an external fixation systemfor holding bone fragments adjacent to each other with the help offixation elements, comprises at least one clamping assembly having atleast one reception to accommodate a fixation element along thelongitudinal axis of the reception and at least one locking elementextending through the clamping assembly which locking element provides aclamping force to clamp the fixation element upon tensioning the lockingelement. The fixation clamp comprises an actuation element which is inconnection with the locking element such that the locking element isactuateable by means of the actuation element, and the actuation elementis designed such that it is detachable from the locking element afteruse and that remounting onto the locking element is prevented afterhaving detached the actuation element from the locking element.

By means of the actuation element the locking element can bepre-tensioned or pre-tightened. After removal of the actuation element aconventional tool can be use to tighten the locking element firmly.Since the actuation element is provided such that it is not remountableonce it has been detached from the locking element, the user is able toseparate used or non-used fixation clamps.

Preferably the actuation element is designed as single-use or disposableelement.

Preferably the actuation element is provided with at least one latchingelement which engages with the locking element. Alternatively theactuation element comprises at least two or at least three latchingelements which are arranged diagonally with respect to the lockingelement from each other. Thereby the latching elements are arranged suchthat it is not possible to spread the latching element by means of atool such as a screwdriver which means that with such a configurationthe risk that the user remounts the actuation element becomes evensmaller.

Further embodiments of the invention are set forth in the dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the followingwith reference to the drawings, which are for the purpose ofillustrating the present preferred embodiments of the invention and notfor the purpose of limiting the same. In the drawings,

FIG. 1 shows a perspective view of a first embodiment of a fixationclamp of the present invention;

FIG. 2 shows a cross-section of the fixation clamp according to FIG. 1;

FIG. 3 shows a top view of the fixation clamp for FIG. 1;

FIG. 4 shows a perspective view from the top of an actuation elementwhich is connectable to the fixation clamp of FIG. 1;

FIG. 5 shows a perspective view from the bottom of the actuation elementof FIG. 4;

FIG. 6 shows a cross-sectional view of the actuation element of FIG. 4;

FIG. 7 shows a perspective view of the fixation clamp of FIG. 1 and theactuation element of FIG. 4 before mounting the actuation element ontothe fixation clamp;

FIG. 8 shows a cross-sectional view of FIG. 7;

FIG. 9 shows a cross-sectional view of the arrangement of FIG. 7 in apre-assembled state;

FIG. 10 shows a cross-sectional view of the arrangement of FIG. 7 duringassembly; and

FIG. 11 shows a cross-sectional view of the arrangement of FIG. 7 afterassembly.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a preferred first embodiment of a clamping element orfixation clamp 10 pursuant to the invention. The clamping element 10consists of a first clamping assembly 20 and a second clamping assembly30 and a locking element or shaft 40 which is positioned through bores21, 31 within the two clamp assemblies 20, 30 along the longitudinalaxis M of shaft 40. The shaft 40 is preferably a locking element adaptedto allow closing the clamp assemblies 20 and 30. Shaft 40 enters a firstjaw 11 through a washer 41.

The shaft 40 comprises a head portion 44, a reduced diameter portion 43which is followed by a shaft portion 42 and a thread portion 49. Theouter threaded portion 49 is adapted to be screwed into a complementaryinner thread within the distal jaw 11 so that turning the head of theshaft 40 changes the longitudinal position of the shaft 40 against thelower jaw 11, which allows opening or closing the entire clamp 10against the force of a spring 15 provided between the two clampassemblies 20 and 30. Spring 15 is preferably positioned incorresponding receptions 16 in the jaws 12. Instead of a spring 15,provided around shaft 40, it is possible to provide a different springmeans as Belleville washers or an elastic compressible solid or foam.Upon closing of the clamp assemblies 20 and 30 the jaws 12 adjacent tothe spring 15 can eventually come into contact and then theanti-rotation surfaced 55 which are provided in both surfaces of thejaws 12 to fix the angular orientation of each clamping assembly 20 and30 against the other.

Preferably after having mounted the shaft 40 with the thread 49 withinthe lower jaw 11, the end portion of the thread 49 is destroyed throughpressure and deformation to ensure that the shaft 40 cannot be removedfrom the clamping assemblies 20, 30 to maintain the clamp as one singlepiece.

Each clamping assembly 20 or 30 comprises two opposing clamping jaws 11and 12. These jaws 11 and 12 are essentially similarly shaped on thesides facing each other. Each of the jaws 12, 11 comprises a respectivecontact surface 18, 19 facing the other surface of the jaw 11, 12.

In order to prevent rotation between the jaw 11 and the jaw 12 as wellas in order to prevent a misalignment of the jaw 11, 12 at least oneorientation device 13, 14 is arranged on the surfaces 18, 19. In thepresent embodiment in the second clamping assembly 30 the jaw 11comprises an opening 14 such as a counterbone extending into surface 18and the jaw 12 comprises a pin 13 extending from surface 19. The pin 13extends into the opening 14. This pin-opening connection preventstherefore a possible rotation between the jaws 11, 12 and a possiblemisalignment between the jaws 11, 12.

The jaws 11 and 12 are provided here with three grooves 51, 52 and 53.Grooves 51, 52 and 53 are all provided in a same plane perpendicular tothe longitudinal axis of shaft 40. In that plane they are orientedperpendicular to the radial direction from the center of the bore 21 or31. As such the grooves 51, 52 and 53 are substantially parallel toouter side wall 61, 62 or 63 of each pair of jaws 11 and 12.

Each pair of grooves 51, 52 or 53, respectively, in each jaw 11 and 12,define one recess or reception, i.e., a first reception 71, a secondreception 72 and a third reception 73. The grooves 51, 52 and 53 areeach formed as a rounded semi-spherical recess in section to providereceptions 71, 72 and 73 which accommodate cylindrical pins or rods witha defined diameter, if the clamp is closed. The outer side walls 61, 62or 63 can comprise an inclined sliding surface to allow an easierclipping of such pins or rods 100 into the corresponding reception. Thegrooves 51, 52, 53 are called to form rounded semi-spherical recesses ina section. This means that the recesses provided by the grooves 51, 52,53 have a hollow cylindrical shape to accommodate rod-shaped elements.Some or all of the grooves 51, 52, and 53 are also provided withfriction enhancing elements such as ribs 56.

All three grooves 51, 52 and 53 have different sizes so that thecorresponding receptions 71, 72 and 73 have three different sizes. Inother words each reception 71, 72 or 73 is adapted to accept a differentfixation element, i.e. a rod, screw, pin or wire having a differentdiameter. One preferred embodiment of the first clamping assembly 20 hasgrooves to accept fixation elements having a diameter of 12 mm, 8 mm and5 mm, respectively. A different embodiment may have a sequence ofdiameters of 8 mm, 6 mm and 4 mm, respectively.

The second clamping assembly 30 according to the embodiment of FIG. 1also comprises two jaw portions 11 and 12 and these comprise threegrooves 51, 52, 53. These grooves 51, 52, 53 also comprise a sequence ofdifferent sizes. In the embodiment shown the inner jaws portion 12 havean identical structure as have the outer jaws 11, especially in view ofthe anti-rotation device 55, the reception 16 for a spring 15.

Within a preferred embodiment the first clamping assembly 20 maycomprise a sequence of smaller sizes, e.g. 7 mm, 5 mm and 3 mm; or 6 mm,5 mm and 4 mm; and the second clamping assembly 30 may comprise asequence of larger sizes, e.g. 13.5 mm, 12 mm and 10 mm. Different sizesare possible, usually for wires starting from 2 mm diameter untilthicker rods with a diameter of 30 mm are used within such a clamp 10.Such a clamp allows using one single versatile clamp, wherein the firstclamping assembly 20 is used to fix a specific pin or screw or wirehaving a diameter for which one of the receptions 71, 72 or 73 isadapted. The user takes the clamp 10 and orients the first clampingassembly 20 into the correct alignment so that the pin or screw can beclipped into the corresponding reception.

Then the clamp 10 can be clamped on a rod of an external fixator withthe help of the second clamping assembly 30. Second clamping assembly 30can be oriented in a way so that the rod can be clipped into thecorresponding reception. It is an advantage of the clamp 10 having twoclamping assemblies 20 and 30 according to the invention, that apractitioner attaching such a clamp at a bone screw with one clampingassembly 20 and subsequently a rod of an external fixator to the otherclamping assembly 30 can check the robustness of his external fixator,and if he finds that the rod he has used is not stiff enough, he simplyopens the second clamping assembly 30, removes the thinner rod, turnsthe second clamping assembly 30 e.g. 60 degrees into one direction orthe other around the longitudinal axis to align the larger receptionwith the new thicker rod and replaces it. This change does notnecessitate the replacement of the clamp 10 itself as necessary withprior art systems. The method to replace such a rod is faster and morereliable since the clamping of the bone screw is not changed, and avoidsuse of a second sterile clamp at said time.

It is of course also possible that the second clamping assembly 30 is atraditional clamping assembly or even any other element known in theprior art with clamping elements. The object of a versatile clampingassembly is already achieved through one first clamping assembly 20,since it allows clamping one of three different sizes of screws, pins ofwires through simple reorientation of the first clamping assembly 20.

FIG. 2 shows a cross-section of the clamp according to FIG. 1, whereinthe clamp 10 is shown in a premounted or preassembled state, i.e. thespring 15 is under tension. The upper jaw 11 of the first clampingassembly 20 is therefore pushing the washer 41 against a flange 45 ofthe head of shaft 40. The bore 21 which accommodates part of the shaftportion 42 and the reduced diameter portion 43 is provided with a largerdiameter than the respective diameter of the shaft 40 so that an angularor pivoting movement of the first clamping assembly 20 against the shaft40 is possible. This is in particularly advantageous during the mountingprocess of the fixation clamp. In this regard it has to be noted thatalso bore 31 can be provided with a larger diameter than the respectivesection of the shaft 40 such that jaw 12 of the second clamping assemblybecomes pivotable to the shaft 40.

The diameter D1, D2 of bore 21 of the first clamping assembly 20 islarger than the diameter of the locking element 40 extending through thebore 21. Thereby a pivoting movement or displacement between the lockingelement 40 and the first clamping assembly 20 during positioning theclamping assemblies 20, 30 and the pins or rods becomes possible. In thepresent embodiment the bore 21 in the first jaw 11 is a bore 21 havingan abutment surface 86. The abutment surface 86 is provided by means astep-like bore 21 having a first section with a first diameter D1 and asecond section with a second diameter D2. The first diameter D1 islarger than the second diameter D2. The abutment surface 86 serves asabutment element for the locking element 40 in particular for the flange45 in case washer 41 is removed. Hence the abutment surface 86 togetherwith the flange prevents that the first clamping assembly 20 will beseparated from the second clamping assembly 30 when the washer isremoved. Particularly during a cleaning or sterilization process theprevention of such a separation is very advantageous.

Alternatively the bore 21 can be provided with a conical section 32 asshown with bore 21 in the jaw 12 of the first clamping assembly. In thepresent embodiment there are two conical sections arranged, whereby thediameter of the bore 21 decreases with increasing length of the bore asseen from outside of the jaw 12. In case two conical sections 32 arepresent the degree of the pivoting motion can be increased.

The shaft 40 as part of a locking element is threaded into the lower jaw11 of the second clamping assembly 30. Hence the lower jaw 11 comprisesa threaded opening. Threading may be provided in the bore or the screwmay exhibit self-tapping threading. Quite generally, a locking elementmay be provided which may be a lever locking element or a bayonet lock.Among these locking elements may also be supporting disks or tootheddisks, which, for the sake of simplicity, are not shown in the drawings.

Therefore the two clamp assemblies 20, 30 can be opened and closedthrough turning the head of shaft 40 and thus turning shaft 40 in thejaw thread.

In the cross-sectional view of FIG. 2 it can also be seen that thelocking element 40 extends through the first clamping assembly 20 and isin contact with the second clamping assembly 30 by means of the threadedportion 49. In mounting position in which the rods or pins will bepositioned in the receptions 71, 72, 73 the first clamping assembly 20is moveable along the middle axis M of the threaded portion 49. Uponactuation of the locking element 40 the first clamping assembly 20 willbe moved against the spring pressure towards the second clampingassembly 30 such that the anti-rotation surface 55 of the first clampingassembly 20 comes into contact with the respective anti-rotation surface55 of the second clamping assembly 30. Once the locking element 40 isfirmly tightened the first clamping assembly 20 and the second clampingassembly 30 are in contact with each other via the anti-rotation surface55.

In FIG. 2 the mounting position of clamping assemblies 20, 30 is shown.Thereby the clamping assemblies 20, 30 are positioned at the distance toeach other with regard to the middle axis M. The second clampingassembly 20 is in contact with the locking element 40 and the spring 15pushes the first clamping assembly away from the second clampingassembly 20 towards the washer 41 which is contact with the flange 45 ofthe locking element.

To summarize: The clamping assemblies 20, 30 will be moved due toactuation of the locking element 40 from a mounting position to alocking position and afterwards when fixation shall be cancelled fromthe locking position to the mounting position. After use the washer 41will be removed as explained below in order to sterilize the clampingelement 10 for further use.

FIG. 3 shows a view from above on the clamp according to FIGS. 1 and 2.Since the embodiment of FIG. 1 comprises three grooves 51, 52 and 53,there are three side walls 61, 62 and 63, which provide, when lookedfrom above as in FIG. 2 a triangular shape of each clamping assembly 20or 30.

The clamping element 10 further comprises an actuation element 90 orthumbwheel which is used to pretighten the locking element 40 before itis tightened by means of a tool such as a wrench. Such an actuationelement 90 is shown in FIGS. 4 to 11, whereby in those figures thefixation clamp according to FIGS. 1 and 3 is shown. For the sake ofsimplicity not all reference numerals regarding the fixation clamp 10have been added.

FIGS. 4 to 6 show views of an actuation element 90 to actuate thelocking element 40 in order to pretighten the fixation clamp 10 by hand.The actuation element 90 is designed as single use element. Preferablythe actuation element 90 is mounted onto the locking element 40 duringor shortly after the process of sterilizing the fixation clamp 10. Afterpretightening the fixation clamp 10 the actuation element 90 is removedby the user, e.g. a surgeon or an assistant of the surgeon. The userthen is able to tighten the locking element 40 by means of a tool thatengages the head portion 44 of the locking element. Since the actuationelement 90 is designed as single use element it is not possible toremount the actuation element 90 onto the locking element 40 afterhaving it detached from the locking element 90. This has the advantagethe one can easily recognize, if the fixation clamp 10 has already beenused or if it is still ready to be used, e.g. if it is still sterilized.

To summarize: the actuation element 90 is designed such that it ismountable by means of a mounting tool 110 onto the locking element 40,that it is detachable from the locking element 40 after use and thatremounting onto the locking element 40 is prevented after havingdetached the actuation element 90 from the locking element 40.

Hence the actuation element 90 is provided in mainly three states,namely in a mounting state in which the actuation element 90 is mountedonto the fixation clamp 10, in a mounted state in which the actuationelement 90 is fixedly connected with the locking element 40 and in adetached state in which the actuation element 90 is detached from thelocking element 10 and in which it is impossible to remount theactuation element 90. In the mounted state the fixation clamp 10 isready for use in a surgery.

The actuation element 90 comprises in the present embodiment, a sidewall93 which may be cylindrical or scalloped, a frontwall 95 extendingsubstantially perpendicular to sidewall 93, a central opening 92extending along a middle axis M2 substantially parallel to sidewall 93and at least one, here four, latching elements 91. The sidewall 93 andthe frontwall 95 encompass an interior space 94 in which the latchingelements 91 extend. The latching elements 91 extend from the frontwall95 in direction of middle axis M2 into said interior space 94 and aredesigned to engage with the locking element 40.

The latching elements 91 are provided as elastic or resilientdeflectable beam elements having a first end 98 which is in contact withthe sidewall 93 or the frontwall 95 and a second end 99 which isprovided as loose or free end. In the present embodiment the first end98 is in contact with or connected to with the frontwall 95 and thefirst end 98 extends over a first segment 101 substantially parallel tofrontwall 95 and over a second segment 102 substantially perpendicularor angular to frontwall 95. Latching elements 91 are elasticallydeformable by means of a mounting tool 110 from a blocking position inwhich the locking element 40 is not insertable into the actuationelement 90 to a mounting position in which the actuation element 90 ismounteable onto the locking 40.

The second end or loose end 99 is provided with an engaging element 97which engages with the locking element 40. The engaging element 97 herehas the shape of an embossment extending from the loose or free end 99into the interior space 94.

Reference is made to the cross-sectional view of the actuation element90 in FIG. 6. The actuation element 90 will be moved along its middleaxis M1 with respect to the locking element 40. In the presentembodiment the locking element 40 enters the interior space from belowin FIG. 6 as indicated by arrow 200.

In the vicinity of each second end 99 there is arranged an abutmentsurface 96. The abutment surface 96 is arranged substantiallyperpendicular to middle axis M2 and extends into the central opening 92.In case the user tries to remount the actuation element 90 onto thelocking element 40 the abutment surface 96 blocks the locking element 40from intruding into the interior space 94. Hence the abutment surface 96blocks a movement of the locking element 40 into the interior space 94as it extends into the path of the locking element 40.

The latching element 91 in the present embodiment is provided with anoptional guiding slot 103 which extends as seen from the central opening92 or the middle axis M2 into the latching element 91. Guiding slot 103serves to accommodate a respective counter part of the mounting tool110.

The actuation element 90 comprises furthermore an outer surface oncylindrical sidewall 93 which outer surface comprises friction enhancingelements 100 in order to increase friction between a user's hand and theactuation element. In the present embodiment the friction enhancingelements 100 are hollow channels extending in direction of the middleaxis M2 into sidewall 93. Furthermore the sidewall 93 comprises alsorecesses 104 extending into sidewall 93.

From FIGS. 1 and 2 it can be seen that the locking element 40 comprisesin its head portion 44 adjacent to flange several recesses 46. In thepresent embodiment the head portion comprises several, here four sidesurfaces 48 extending from the flange 45 along middle axis M. The headportion 44 ends with a top surface 47 which is arranged substantiallyperpendicular to the middle axis M and to the side surfaces 48. The topsurface 47 here is slightly convex. The side surfaces 48 serve asengaging surface for a tool in order to tighten the locking element 40.In the present embodiment the recesses 46 extend into the head portion44, in particular into the side surfaces 48 of the locking element 40.

Reference is now made to FIGS. 7 and 8 in which the actuation element 90is shown above the fixation clamp 10. Furthermore a mounting tool 110 tomount the actuation element 90 onto the fixation clamp 10 is shown. Themounting tool 110 is used to mount the actuation element 90 onto thelocking element during or shortly after sterilizing the fixation clamp10. The mounting tool 110 mainly serves to push the latching elementaway from the middle axis M2 so that the clearance between the latchingelements 91 becomes larger in order to receive the head portion 44 ofthe locking element 40. With other words it can also be said that theabutment surfaces 96 will be moved away from the middle axis M2 suchthat they give way for the head portion 44.

The mounting tool 110 comprises a tool section 111 and a handle section112. The tool section 111 is provided such that the mounting tool 110can be inserted into the central opening 92 and pushes the latchingelements 91 away from the middle axis M2 in order to enlarge theclearance between the latching elements 91. In case the latchingelements 91 are provided with the guiding slots 103 the tool section 111comprises a respective embossment 113 that is adapted to engage into theguiding slot 103. The handle section 112 is provided such that it can begrasped by a hand of a mounting person.

In FIG. 9 it is shown that the mounting tool 110 will be inserted withthe tool section 111 into the central opening 92. This is shown by arrow201. Thereby the latching elements 91 will be moved away from the middleaxis M2. Hence the abutment surfaces 96 as well as the engaging elements97 will be moved away from the middle axis M2 towards the sidewall 93.

FIG. 10 shows the actuation element 90 in the mounting state in whichthe actuation element 90 will be moved towards the fixation clamp 10 indirection of arrow 202, wherein the head portion 44 of the lockingelement 40 extends into the interior space 94 between the latchingelements 91. The latching element 91 is thereby in contact with the sidesurface 48 of the locking element 40 and therefore it is possible tomove the actuation element 90 with respect to the locking element 40.

FIG. 11 shows the end position of the actuation element 90 with regardto the locking element 40. Thereby the actuation element 90 is in aposition in which the engaging elements 97 are able to engage into therecesses 46 of the locking element 40. Once the actuation element 90 hasreached its end position as shown in FIG. 11 the resilient latchingelements 91 will move to their originating position and engage into therecesses 46. In this state the fixation clamp 10 is ready to be used bya user in a operating theatre during a surgery.

Once the user has pretensioned or pretightened the fixation clamp 10 bymeans of the actuation element 90, the actuation element 90 isdetachable from the locking element 10. In order to enhance thisdetaching process the recesses 46 comprise chamfered edges 460 which areinclined towards the middle axis M1 such that the latching elements 91will be moved away from the middle axis M2 upon a displacement of theactuation element 90 relative to the recess 46. Afterwards withincreasing distance between the fixation clamp 10 and the actuationelement 90 the latching elements 91 are in contact with the sidesurfaces 48 of the locking element 40 and slides on these surfaces.During detaching the actuation element 90 the user has to apply a forcein direction of arrow 203 as shown in FIG. 11.

Once the actuation element 90 is completely detached from the lockingelement 40, the latching elements 91 will move back to their originposition due to the resilient structure. Thereby the abutment surfaces96 are arranged such that the locking element 40 abuts with its topsurface 47 on the abutment surfaces 96. Hence it is not possible toremount the actuation element 90.

The actuation element 90 is preferably made out of plastic material, inparticular out of a thermoplastic.

The actuation element 90 has the following advantages: First of all itis possible to pretighten the fixation clamp 10 by hand without the aidof an additional tool. Furthermore the user is able to recognize, if thefixation clamp is ready for use when the actuation element 90 is stillmounted or, if the fixation clamp has been used in which case theactuation element is removed. Furthermore false use is prevented due tothe fact that the actuation element 90 cannot be remounted without theaid of a respective tool.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A fixation clamp for use in an external fixation system for holdingbone fragments adjacent to each other with the help of fixationelements, said clamp comprising: at least one clamping assembly havingat least one reception to accommodate a fixation element along thelongitudinal axis of the reception and at least one locking elementextending through the clamping assembly which locking element provides aclamping force to clamp the fixation element upon tensioning the lockingelement and, an actuation element which is in connection with thelocking element such that the locking element is actuateable by means ofthe actuation element, wherein the actuation element is designed suchthat it is detachable from the locking element after use and thatremounting onto the locking element is prevented after having detachedthe actuation element from the locking element.
 2. The fixation clampaccording to claim 1, wherein the actuation element is designed assingle-use element.
 3. The fixation clamp according to claim 1, whereinthe actuation element is designed as disposable element.
 4. The fixationclamp according to claim 1, wherein the actuation element is providedwith at least one latching element which engages with the lockingelement
 5. The fixation clamp according to claim 1, wherein theactuation element comprises at least two latching elements which arearranged diagonally with respect to the locking element from each other.6. The fixation clamp according to claim 1, wherein the actuationelement comprises at least three latching elements which are arrangeddiagonally with respect to the locking element from each other.
 7. Thefixation clamp according to claim 1, wherein the actuation elementcomprises a central opening extending along a middle axis and at leastone of said latching elements extending in direction said centralopening.
 8. The fixation clamp according to claim 1, wherein theactuation element comprises a substantially cylindrical sidewallproviding an interior space and a frontwall extending from said sidewallinto the interior space, whereby the frontwall comprises said centralopening along which said latching element(s) extend.
 9. The fixationclamp according to claim 1, wherein the head portion of the lockingelement comprises a top surface extending substantially perpendicular toa middle axis of the locking element and a plurality of side surfacesextending substantially parallel to said middle axis, wherein therecesses extend into said side surfaces.
 10. The fixation clampaccording to claim 1, wherein the latching element comprise an abutmentsurface which is arranged such that it abuts against the locking elementwhile remounting the actuation element.
 11. The fixation clamp accordingto claim 1, wherein the latching element comprise an abutment surfacewhich is arranged such that it abuts against the top surface of thelocking element while remounting the actuation element.
 12. The fixationclamp according to claim 1, wherein the latching elements are by meansof a mounting tool elastically deformable from a blocking position to amounting position, wherein in said blocking position the latchingelements are positioned such that they abut onto the locking element inorder to prevent remounting and wherein in said mounting position thelatching elements are positioned such that the actuation element ismoveable with respect to the locking element.
 13. The fixation clampaccording to claim 1, wherein said mounting tool deformes said latchingelements towards the sidewall such that the clearance between thelatching elements will be enlarged in order to receive the lockingelement.
 14. The fixation clamp according to claim 1, wherein thelatching elements are provided as elastic or resilient beam elementshaving a first end which is in contact with the sidewall or thefrontwall and a second end which is provided as loose end.
 15. Thefixation clamp according to claim 1, wherein the latching elementcomprises an engaging element which engages with the locking element,preferably in said recesses.
 16. The fixation clamp according to claim1, wherein the engaging element and/or the abutment surface are arrangedin the vicinity of said second end.
 17. The fixation clamp according toclaim 1, wherein the actuation element comprises an outer surface havingfriction enhancing elements in order to increase friction between auser's hand and the actuation element.
 18. A fixation clamp for use inan external fixation system for holding bone fragments adjacent to eachother with the help of fixation elements, said clamp comprising at leastone clamping assembly having at least one reception opening toaccommodate a fixation element along a longitudinal axis of thereception opening and at least one locking element extending through theclamping assembly which locking element provides a clamping force toclamp the fixation element upon tensioning the locking element, and anactuation element which is in connection with the locking element suchthat the locking element is actuateable by means of the actuationelement wherein the actuation element comprises at least one latchingelement having an abutment surface, wherein said latching elementengages with the locking element and is adapted such that the actuationelement is detachable from the locking element after use, and whereinthe abutment surface is arranged such that it abuts against the lockingelement while remounting the actuation element onto the locking element.19. The fixation clamp according to claim 18, wherein the actuationelement comprises at least two latching elements which are arrangeddiagonally with respect to the locking element from each other.
 20. Thefixation clamp according to claim 19, wherein the actuation elementcomprises a central opening extending along a middle axis and at leastone of said latching elements extending in direction said centralopening.
 21. The fixation clamp according to claim 20, wherein theactuation element comprises a substantially cylindrical sidewallproviding an interior space and a frontwall extending from said sidewallinto the interior space, whereby the frontwall comprises said centralopening along which said latching element(s) extend.
 22. The fixationclamp according to claim 20, wherein the locking element comprisesrecesses in which the latching elements engage, wherein said recessesextend into a head portion of the locking element.
 23. The fixationclamp according to claim 20, wherein the head portion of the lockingelement comprises a top surface extending substantially perpendicular toa middle axis of the locking element and a plurality of side surfacesextending substantially parallel to said middle axis, wherein therecesses extend into said side surfaces.
 24. The fixation clampaccording to claim 20, wherein the abutment surface is arranged suchthat it abuts against the top surface of the locking element whileremounting the actuation element.
 25. A tool adapted to remount anactuation element onto a fixation clamp according to claim 1, whereinthe tool comprises a tool section adapted to engage with said latchingelements and to push said latching elements away from the middle axis sothat the actuation element is mountable onto said locking element of asterilized fixation clamp.
 26. A tool adapted to remount an actuationelement onto a fixation clamp according to claim 20, wherein the toolcomprises a tool section adapted to engage with said latching elementsand to push said latching elements away from the middle axis so that theactuation element is mountable onto said locking element of a sterilizedfixation clamp.
 27. The fixation clamp according to claim 1, wherein theactuation element comprises a stop element for engaging the lockingelement to prevent reattachment of the actuation element.
 28. Thefixation clamp according to claim 18, wherein the abutment surfaceserves as a stop element for engaging the locking element to preventreattachment of the actuation element.
 29. A fixation clamp for use inan external fixation system for holding bone fragments adjacent to eachother with the help of fixation elements, said clamp comprising: atleast one clamping assembly having at least one reception to accommodatea fixation element along the longitudinal axis of the reception and atleast one locking element extending through the clamping assembly whichlocking element provides a clamping force to clamp the fixation elementupon tensioning the locking element and, an actuation element which isin connection with the locking element such that the locking element isactuateable by means of the actuation element, wherein the actuationelement is designed such that it is detachable from the locking elementafter use and that remounting onto the locking element is preventedafter having detached the actuation element from the locking element andwherein the locking element comprises recessed in which the latchingelements engage, wherein said recesses extend into a head portion of thelocking element.